From 94ee47c6e45f90acf560e472b04fef5f28317037 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 20 Feb 2023 12:22:16 -0700
Subject: [PATCH] [qu2cu] Add a test and fix a bug

---
 Lib/fontTools/pens/qu2cuPen.py | 35 ++++++++++++++++++----------------
 Lib/fontTools/qu2cu/qu2cu.py   |  2 +-
 Tests/pens/qu2cuPen_test.py    | 25 ++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 17 deletions(-)

diff --git a/Lib/fontTools/pens/qu2cuPen.py b/Lib/fontTools/pens/qu2cuPen.py
index d0b42c42c..caf49d41c 100644
--- a/Lib/fontTools/pens/qu2cuPen.py
+++ b/Lib/fontTools/pens/qu2cuPen.py
@@ -49,7 +49,7 @@ class Qu2CuPen(ContourFilterPen):
         self.stats = stats
 
     def _quadratics_to_curve(self, q):
-        curves = quadratic_to_curves(q, self.max_err, self.all_cubic)
+        curves = quadratic_to_curves(q, self.max_err, all_cubic=self.all_cubic)
         if self.stats is not None:
             n = str(len(curves))
             self.stats[n] = self.stats.get(n, 0) + 1
@@ -81,21 +81,24 @@ class Qu2CuPen(ContourFilterPen):
         if quadratics:
             newContour.extend(self._quadratics_to_curve(quadratics))
 
-        # Add back implicit oncurve points
-        contour = newContour
-        newContour = []
-        for op, args in contour:
-            if op == "qCurveTo" and newContour and newContour[-1][0] == "qCurveTo":
-                pt0 = newContour[-1][1][-2]
-                pt1 = newContour[-1][1][-1]
-                pt2 = args[0]
-                if math.isclose(pt2[0] - pt1[0], pt1[0] - pt0[0]) and math.isclose(
-                    pt2[1] - pt1[1], pt1[1] - pt0[1]
-                ):
-                    newArgs = newContour[-1][1][:-1] + args
-                    newContour[-1] = (op, newArgs)
-                    continue
+        if not self.all_cubic:
+            # Add back implicit oncurve points
+            contour = newContour
+            newContour = []
+            for op, args in contour:
+                if op == "qCurveTo" and newContour and newContour[-1][0] == "qCurveTo":
+                    pt0 = newContour[-1][1][-2]
+                    pt1 = newContour[-1][1][-1]
+                    pt2 = args[0]
+                    if (
+                        pt1 is not None
+                        and math.isclose(pt2[0] - pt1[0], pt1[0] - pt0[0])
+                        and math.isclose(pt2[1] - pt1[1], pt1[1] - pt0[1])
+                    ):
+                        newArgs = newContour[-1][1][:-1] + args
+                        newContour[-1] = (op, newArgs)
+                        continue
 
-            newContour.append((op, args))
+                newContour.append((op, args))
 
         return newContour
diff --git a/Lib/fontTools/qu2cu/qu2cu.py b/Lib/fontTools/qu2cu/qu2cu.py
index 20bfaa93f..ffe9d9402 100644
--- a/Lib/fontTools/qu2cu/qu2cu.py
+++ b/Lib/fontTools/qu2cu/qu2cu.py
@@ -253,7 +253,7 @@ def spline_to_curves(q, costs, tolerance=0.5, all_cubic=False):
     # cubic curves, and within those the one with smallest error.
     sols = [Solution(0, 0, 0, False)]
     for i in range(1, len(elevated_quadratics) + 1):
-        best_sol = Solution(len(q) + 2, 0, 1, False)
+        best_sol = Solution(len(q) + 4, 0, 1, False) # Impossible
         for j in range(0, i):
 
             j_sol_count, j_sol_error = sols[j].num_points, sols[j].error
diff --git a/Tests/pens/qu2cuPen_test.py b/Tests/pens/qu2cuPen_test.py
index f3f8a3f7c..acb09db5e 100644
--- a/Tests/pens/qu2cuPen_test.py
+++ b/Tests/pens/qu2cuPen_test.py
@@ -219,6 +219,31 @@ class TestQu2CuPen(unittest.TestCase, _TestPenMixin):
             ],
         )
 
+    def test_all_cubic(self):
+        inPen = RecordingPen()
+        inPen.value = [
+            ("moveTo", ((1204, 347),)),
+            ("qCurveTo", ((1255, 347), (1323, 433), (1323, 467))),
+            ("qCurveTo", ((1323, 478), (1310, 492), (1302, 492))),
+            ("qCurveTo", ((1295, 492), (1289, 484))),
+            ("lineTo", ((1272, 461),)),
+            ("qCurveTo", ((1256, 439), (1221, 416), (1200, 416))),
+            ("qCurveTo", ((1181, 416), (1141, 440), (1141, 462))),
+            ("qCurveTo", ((1141, 484), (1190, 565), (1190, 594))),
+            ("qCurveTo", ((1190, 607), (1181, 634), (1168, 634))),
+            ("qCurveTo", ((1149, 634), (1146, 583), (1081, 496), (1081, 463))),
+            ("qCurveTo", ((1081, 417), (1164, 347), (1204, 347))),
+            ("closePath", ()),
+        ]
+
+        outPen = RecordingPen()
+        q2cPen = Qu2CuPen(outPen, 1.0, all_cubic=True)
+        inPen.replay(q2cPen)
+
+        print(outPen.value)
+
+        assert not any(typ == "qCurveTo" for typ, _ in outPen.value)
+
 
 if __name__ == "__main__":
     unittest.main()